An examination of the ellipticity of the earth's equatorial section that causes appreciable perturbations in the motion of a synchronous satellite relative to the earth. This memorandum extends the analysis to include circular equatorial orbits other than synchronous. It is found that the only orbits other than synchronous that are appreciably perturbed by ellipticity are those with 12- and 36-hour periods. The resulting perturbation is a divergent oscillation in both orbital radius and orbital angular position. Actually, the rate of divergence is very slow, and, as a result, the major station-keeping problem is still the steady-state drift in angular position resulting from residual errors in initial orbital radius and orbital velocity. The earth's equatorial ellipticity provides no stabilization to orbital rate that could be used for station-keeping contrary to the recent proposal on "Natural Station-Keeping" by the ROSAE Corporation
This report is part of the RAND Corporation Research memorandum series. The Research Memorandum was a product of the RAND Corporation from 1948 to 1973 that represented working papers meant to report current results of RAND research to appropriate audiences.
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